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Subject: AW: AW: AW: Still Problems with AJB Remote
From: Matthias Klumpp (Matthias.Klumpp_at_gmx.de)
Date: 2004-07-13


Hi Jörg,

many thanks for your help (please have another short look below).

# -----Ursprüngliche Nachricht-----
# The "circuit" is very simple: connect the source to the Archos, drain to
# your TTL input/output, gate to a 3.3V reference. The transistor draws no
# power from there, it's just a reference. However you do this, maybe a
# voltage divider from 5V. (eg, 22kOhm towards ground and 12 kOhm towards 5V
# will give 3.2V at the midpoint)
#
# If your Archos needs an external pullup, you can connect it via maybe
# 4.7kOhm to 5V. This is safe, the pin is capable to limit the voltage if
the
# current is limited by such a resistor.
#
# I'm no good in ASCII drawing, but I hope it's understandable without.

So I'll do it, just to be sure:

  +5V
   |
   +-------------------------------+
   | |
  +-+ +-+
  | |22k | |4.7k
  | | | |
  +-+ +-+
   +---------------------+ |
  +-+ | |
  | |12k | |
  | | | |
  +-+ | |
   | | |
   | | |
  --- | |
                         |G |
                      ------ |
                      D| |S |
    uC Out port--------+ +--------+-- AJB remote

Like this ?

I would like to have a "universal" circuit, that works with both (AJB with
and without internal pull-ups).

Does this schematic work both ways or do I have to take out the 4.7k, if I
already have the pull-up inside the AJB ?

Gruß / Regards / Abraço

Matthias

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